Afraid that the other is going to attack so they build deterrents such as nuclear bombs to keep the other from attacking.
Answer:
Civil wars. Probably the most important single cause of Byzantium's collapse was its recurrent debilitating civil wars. Three of the worst periods of civil war and internal infighting took place during Byzantium's decline.
Explanation:
If you traveled to the Spanish city of Cordoba in the tenth century, you would find prosperous trading and religious center, a population larger than Paris, France and a cultural center for the region. The only thing that is not found is the third choice which states that Cordoba is a government free from Islamic influence.